Images are formed in silver halide color photographic materials by reaction between oxidized silver halide developing agent and a dye forming compound known as a coupler. Photographic properties of the image, such as sharpness, granularity, contrast and color reproduction, can be enhanced by the use of compounds which make available an image modifier during processing. An early embodiment was the release from a coupler during photographic processing of a development inhibitor. These compounds were commonly referred to as development inhibitor releasing (DIR) couplers and were first described in U.S. Pat. Nos. 3,148,062 and 3,227,554.
In U.S. Pat. No. 5,354,650 there is described a photographic element in which an image modifier is made available by the interaction of two compounds. Such a photographic element comprises a support bearing at least one silver halide emulsion layer, and contains:
a) a release compound that provides, as a function of development, an imagewise distribution of a compound A that is photographically inert in the form in which it is released; and PA1 b) a uniform distribution of a compound B, or its precursor, which is photographically inert in the form in which it is contained in the layer; PA1 but under photographic processing conditions compounds A and B interact to provide an image modifying group. PA1 a) a release compound that provides an imagewise distribution of a nucleophile as a function of silver halide development; and PA1 b) a uniform distribution of a dye moiety that is immobilized in the photographic element by a group which is displaceable by the nucleophile; PA1 the nucleophile and the dye moiety being such that they interact under photographic processing conditions to make the dye moiety mobile. Thus, the dye moiety is mobilized, and can be removed from the photographic element, in inverse proportion to the formation of image dye. This provides a convenient alternative to masking couplers. PA1 a support bearing PA1 a cyan dye image-forming unit comprising at least one red-sensitive silver halide emulsion layer having associated therewith at least one cyan dye-forming coupler, PA1 a magenta dye image-forming unit comprising at least one green-sensitive silver halide emulsion layer having associated therewith at least one magenta dye-forming coupler, and PA1 a yellow dye image-forming unit comprising at least one blue-sensitive silver halide emulsion layer having associated therewith at least one yellow dye-forming coupler; and PA1 associated with at least one of the dye image-forming units, PA1 a) a release compound that provides an imagewise distribution of a compound A, compound A comprising a nucleophile that is imagewise releasable from a carrier group as a function of silver halide development; and PA1 b) a uniform distribution of a compound B, compound B comprising a solubilized dye moiety joined by a sulfinate linkage to a blocking group which immobilize the dye moiety in the element and from which it is displaceable by compound A; PA1 compounds A and B, under photographic processing conditions, being capable of interacting to provide an unblocked, mobile, solubilized dye moiety. PA1 R is H or a monovalent substituent; PA1 BALL is a ballast group which renders the compound immobile in the layer in which it is coated; PA1 LINK is a linking group; PA1 n is 0, 1 or 2; and PA1 DYE-SOL is a solubilized dye moiety. PA1 X is N or C--R; PA1 R is hydrogen or a monovalent substituent; PA1 BALL is a ballast group which renders the compound immobile in the layer in which it is coated; PA1 LINK is a linking group; PA1 n is 0, 1, or 2; and PA1 DYE-SOL is a solubilized dye moiety.
By employing compounds A and B, which need to interact in order for the photographically active group to be available in its active form, it is possible to target the location where that group operates. Also, these compounds provide a means for incorporating in a photographic element precursors of photographically active groups that otherwise would be unstable.
U.S. Pat. No. 5,455,141 extends the technology described in U.S. Pat. No. 5,354,650 to the release of dyes in photographic elements. One embodiment described in U.S. Pat. No. 5,455,141 provides an alternative to the masking couplers used in photographic elements. Masking couplers are used extensively in color negative photographic elements to correct for the unwanted absorption of image dyes. The masking effect is obtained by imagewise destruction of a dye which has the same hue as the unwanted absorption for which it corrects. The loss of density due to the destruction of the masking dye offsets the unwanted gain in density due to the unwanted absorptions of the image dye.
In the embodiment of U.S. Pat. No. 5,455,141 of interest here, the the photographic element contains:
The sulfinate blocked dye moieties shown in U.S. Pat. No. 5,455,141, are preferred because of their good reactivity with the preferred thiol nucleophiles as well as because of their poor reactivity with other nucleophiles that are uniformly present in the photographic element or the processing solution. We have found that in multilayer color photographic elements the sulfinate blocked dye moieties described in U.S. Pat. No. 5,455,141 unfortunately are not as mobile as had been expected. As a result, the dye which is released on photographic processing is not completely removed from the photographic element, resulting in less than adequate masking and incorrect color rendition.
Filter dye compounds in which a dye moiety is joined to a ballast moiety via a sulfinate linkage are described, for example, in EP Published Patent Applications 0 483 809 and 0 484 820. However, these dye compounds are uniformly removed from the element on processing, and they contain no suggestion that there would be any difficulty in removal of the dye.
It would be desirable to provide multilayer color photographic elements that employ the masking technology described in U.S. Pat. No. 5,455,141, but which utilize sulfinate blocked dye moieties that readily are removed from the element during photographic processing.